Fuel-injection valve for internal combustion engines

ABSTRACT

An injection valve member for closing or opening injection orifices of a valve seat element is integrated, in a longitudinally displaceable manner, into a central housing bore of a fuel-injection valve. The valve seat element is fixed to the housing and the part of the element that includes the injection orifices and the seat projects out of the housing. Elements for determining the rotational position of the valve seat element in relation to the housing are provided on the exterior of the part. The fuel injection valve requires simple production and assembly engineering and permits a slimline injector configuration for both large and small internal combustion engines.

The invention relates to a fuel injection valve for an intermittent fuelinjection into the combustion space of an internal combustion engine.

A fuel injection valve of this type is disclosed in the older Europeanpatent application, publication number EP-A-1 118 765. The fuelinjection valve has a housing with a central bore which extends in itslongitudinal direction and in which is arranged longitudinallyadjustably an injection valve member which is provided for the closingor opening of injection orifices of a valve seat element fastened in thehousing. The valve seat element is pressed with its upper annular endface sealingly onto a lower annular end face of the housing by means ofa union nut which can be screwed onto the housing. For fixing a definedrotary position of the valve seat element with respect to the housing,one or more pins are provided which run in the longitudinal directionand project into corresponding recesses in the end faces bearing againstone another. In fuel injection valves for small internal combustionengines and for large internal combustion engines in which it isnevertheless important to have a slender injector design, this solutionis unsatisfactory, since the space for these pins is often absent.

The object on which the present invention is based is to provide a fuelinjection valve which is simple and cost-effective in terms ofproduction and of assembly and in which a slender injector design ispossible both for small and for large internal combustion engines. Afurther object is to propose a method for mounting a valve seat elementon a housing of a fuel injection valve.

This object is achieved, according to the invention, by means of a fuelinjection valve having the features of the independent claims 1 or 13and a method according to claim 12.

Preferred developments of the fuel injection valve according to theinvention form the subject matter of the dependent claims.

Fuel injection valves of the type initially mentioned, with aparticularly preferred connection of the valve seat element to thehousing, form the subject matter of the independent claims 16 and 18.

A particularly preferred method for fastening the valve seat element tothe housing of the fuel injection valve is defined in claim 17.

The invention is explained in more detail below with reference to thedrawings in which:

FIG. 1 shows an exemplary embodiment of a fuel injection valve inlongitudinal section;

FIG. 2 shows, on an enlarged scale and in longitudinal section, a lowerpart of the fuel injection valve shown in FIG. 1, with a first exemplaryembodiment of a valve seat element;

FIG. 3 shows a section along the line III-III in FIG. 2;

FIG. 4 shows a section along the line IV-IV in FIG. 2;

FIG. 5 shows an illustration, corresponding to FIG. 2, of a secondembodiment of the lower valve part, with a second exemplary embodimentof a valve seat element;

FIG. 6 shows a variant of the embodiment of the lower valve partaccording to FIG. 5, with a third exemplary embodiment of a valve seatelement;

FIG. 7 shows a fourth exemplary embodiment of a valve seat element;

FIG. 8 shows a third embodiment of the lower valve part;

FIG. 9 shows a fourth embodiment of the lower valve part;

FIG. 10 shows a fifth embodiment of the lower valve part;

FIG. 11 shows a sixth embodiment of the lower valve part;

FIG. 12 shows diagrammatically an exemplary embodiment of a device forthe welded connection of a valve seat element to a valve housing;

FIG. 13 shows a seventh embodiment of the lower valve part;

FIG. 14 shows a eighth embodiment of the lower valve part; and

FIG. 15 shows a ninth embodiment of the lower valve part.

According to FIG. 1, a fuel injection valve 1 is connected via a fuelhigh pressure connection 10 to a high pressure conveying means, notillustrated in the drawing, which delivers fuel with a pressure of 100to 2000 bar and above. Furthermore, the fuel injection valve 1 isconnected to an electronic control, likewise not shown, via electricalconnections 12.

The fuel injection valve 1 has a housing 14 which comprises a lowerhousing part 14 a and an upper housing part 14 b. The lower housing part14 a is of tubular design, is long and is narrow in diameter and has acentral bore 40 coaxial to the longitudinal axis A of the fuel injectionvalve 1. The central bore 40 is widened in the region of the upperhousing part 14 b. This bore of larger diameter is designated by 42 inFIG. 1. A passenger bore 44 connecting the fuel high pressure connection10 to the widened part 42 of the central bore is arranged radially tothe longitudinal axis A.

According to FIGS. 1 and 2, the lower housing part 14 a is connected atits lower end to a screwed-on holding part 16 designed as a union nut.Inserted in the holding part 16 is a nozzle body 18, of which the nozzletip 22 provided with a nozzle needle seat 26 and with a plurality ofinjection orifices 28 projects out of the holding part 16 and forms avalve seat element for a lower end 34 of an axially adjustable nozzleneedle 30 forming an injection valve member. The injection orifices 28of the nozzle tip 22 can be opened and closed by means of the lower end34 of the nozzle needle 30. The nozzle body 18 is pressed with its upperend face 25 onto a lower face 20 of the lower housing part 14 a by meansof the holding part 16 via a washer 23, the metallic washer 23 providedwith lapped end faces cooperating with the corresponding machined endface 25 and lower face 20, as a sealing element.

The nozzle needle 30 extends concentrically to the longitudinal axis Afrom the lower nozzle needle seat 26 through a bore or recess 32 of thenozzle body 18 and through the central bore 40 of the housing part 14 aupwardly and in the upper end part has a collar 35 and a control piston31. The control piston 31 forms part of a control device S1 forcontrolling the adjusting movement of the injection valve member, thatis to say of the nozzle needle 30. The control device S1 illustrated inFIG. 1 corresponds to the control device S1 of the fuel injection valvedescribed in EP-A-1 118 765 (FIGS. 2 and 3). Reference is therefore madeto these patent applications for a detailed description of this controldevice S1 and of its functioning. Only those parts of this controldevice S1 which are important for understanding the basic functioning ofthe fuel injection valve are mentioned further below.

The nozzle needle 30 has, in the region of the nozzle body bore 32, apart 39 which is provided with axially running ground-down faces 36 andby means of which said nozzle needle is closely guided slideably in thebore 32 (a sliding fit of less than 20 μm is provided). The ground-downfaces 36 are also evident from FIG. 4. This part 39 provided withground-down faces 36 is connected to the lower end 34 of the nozzleneedle via a part 38 of stepped diameter. The ground-down faces 36ensure the hydraulic connection of an annular space 37 (cf. FIG. 2)surrounding the part 38 to the central bore 40 of the housing part 14 aor to a space 43 surrounded by this bore 40.

In the exemplary embodiment illustrated in FIG. 1, the nozzle needle 30is of one-piece design. The nozzle needle could, however, also consistof a plurality of elements operatively connected to one another.

A holding nut 17 is screwed onto the upper housing part 14 b. Inside theholding nut 17 is accommodated an electromagnetically actuable pilotvalve 46 which comprises an armature 58 firmly connected to a pilotvalve stem 54. In a currentless state of an electromagnet 50, the pilotvalve stem 54 is pressed downward by the force of a compression spring60. The magnitude of this force can be set by means of a springtensioning element 62. For actuating the pilot valve 46 or for raisingthe pilot valve stem 54 connected to the armature 58, an exciting coil52, assigned to the armature 58, of the electromagnet 50 is supplied viathe electrical connections 12 with control pulses from the electroniccontrol.

The spring tensioning element 62 is accommodated in a closing-off part64 sealingly closing off the fuel injection valve 1 at its upper end.The holding nut 17 has installed in it, together with the electromagnet50, a fuel return connection 66 which is connected to a space 67, whatis known as a low pressure zone, which surrounds the pilot valve 46 andin which fuel of low pressure flows.

The central housing bore 40 or its part 42 of widened diameter issealingly closed off at the top by means of a control body 74 fixed tothe housing. The control body 74, forming part of the control device S1,has an outlet orifice 77 which can be opened or closed as a result ofthe actuation of the pilot valve 46 or by the pilot valve stem 54 beingraised or lowered. The outlet orifice 77 connects a control space 11,arranged above the control piston 31, to the low pressure zone 67. Thecontrol space 11 has, in a way known per se and not described in anymore detail here, a throttle connection to the central housing bore 40which belongs to the high pressure zone connected to the fuel highpressure connection 10.

The control piston 31 is acted upon, on the one hand, by the fuel systempressure prevailing in the high pressure zone and, on the other hand, bythe fuel control pressure in the control space 11. By means of a closingspring or nozzle needle spring 68, which is pretensioned between thecollar 35 of the nozzle needle 30 and a sleeve-shaped part 70,surrounding the control piston 31, of the control device S1, the nozzleneedle 30 is pressed downward in the closing direction of the fuelinjection valve 1 and is held reliably against the fuel high pressureexerted on the nozzle needle 30. The pretensioning force of the nozzleneedle spring 68 must be relatively high and may amount, for example, to100 to 300 N.

The stroke of the nozzle needle 30 is, as a rule, about 0.2 to 0.4 mm.By the choice of a suitable thickness of the washer 23 alreadymentioned, the needle stroke can be adapted in relation to the nozzleneedle seat 26 (tolerance compensation).

FIG. 1 shows the fuel injection valve 1 in a position prior to theinjection operation. In the control space 11 closed by the pilot valvestem 54, the same high pressure prevails as in the high pressure zone,that is to say as in the space 37, 43 which is surrounded by the housingbores 42, 40 and the bore 32 and which extends as far as the nozzleneedle seat 26 and surrounds the nozzle needle 30. As soon as a pulse ofselected duration is supplied to the electromagnet 50 via the electroniccontrol, the armature 58 is pulled out counter to the force of thecompression spring 60 and the pilot valve stem 54 of the pilot valve 46is thus raised. The pilot valve stem 54 opens the outlet orifice 77 ofthe control body 74. The pressure in the control space 11 falls, and theopening movement of the nozzle needle 30 is controlled via the controldevice S1. The injection operation is initiated.

To terminate the injection operation, the pilot valve 46 is brought intoits closing position via the electromagnet 50, again by electroniccontrol. The outlet orifice 77 is closed again, and the pressure in thecontrol space 11 rises again, the sequence of this operation again beingcontrolled by the control device S1.

An essential advantage of the fuel injection valve 1 according to theinvention is that the high pressure zone, that is to say the space 37,43 concentrically surrounding the nozzle needle 30 from the nozzleneedle seat 26 via the bore 32 and the housing bores 40, 42, thepassenger bore 44, and also the control space 11 as far as the outletorifice 77, forms a fully sealed region without leakage points.

By the choice of an appropriate diameter of the central housing bore 40surrounding the nozzle needle 30 in its middle region, the space 43containing the compressible fuel can be defined in varying size in termsof its cross section or of its volume, and, as a result, theinstantaneous transient pressure drop in the high pressure zone duringthe injection operation can be kept within desired limits, depending onthe use of the fuel injection valve 1, that is to say depending on theengine size. In the case of a smaller cross section, that is to say inthe case of a smaller accumulator volume in the high pressure zone, thepressure drop is greater than in the case of a large cross section. Thechoice of a large cross section, that is to say of a larger insidediameter of the central housing bore 40, with the same diameter of thenozzle needle 30, means, however, that the housing wall becomes thinnerin this region, since the outside diameter of the housing 14 or of thelower housing part 14 a cannot be increased, as desired, for reasons ofspace (a slender design of the injector is important for installing thefuel injection valve in the cylinder head of an internal combustionengine). With previous fuel injection valves (cf. the fuel injectionvalve already mentioned according to FIG. 1 of EP-A-1 118 765), aspecific wall thickness of the housing was necessary, so that pinssecuring the defined rotary position of the valve seat element withrespect to the housing could be accommodated. To be precise, while therotary position of the housing 14 is determined by the internalcombustion engine, the nozzle body 18 forming the valve seat elementmust be set and fixed in its rotary position with respect to the housing14 according to the engine design, so that one of the injected fuel jetsreliably enters the region of the glow plug in the combustion space ofthe internal combustion engine.

So that, even in the case of slender injectors, the rotary position ofthe nozzle body 18 can be defined with respect to the housing 14 withoutdifficulty and the diameter of the central housing bore 40 surroundingthe nozzle needle 30 in its middle region can nevertheless at the sametime be selected freely (that is to say, the injectors can also have athin-walled design), according to the invention positioning faces 80running in the axial direction are formed on the circumference of thenozzle body part projecting out of the holding part 16, that is to sayon the circumference of the nozzle tip 22. Preferably, the nozzle tip 22has two parallel plane positioning faces 80, as is evident from FIG. 3.In the exemplary embodiment illustrated in FIGS. 1 and 2 and also inFIG. 4, the nozzle body 18 is also provided in its region located insidethe union nut or the holding part 16 with preferably two reference faces81 parallel to one another and to the positioning faces 80. Thesereference faces 81 serve for positioning or chucking the nozzle body 18provided with the positioning faces 80, during the manufacture of theinjection orifices 28. If, however, both the positioning faces 80 andthe injection orifices 28 are manufactured on the same machine, that isto say with the same chucking, the reference faces 81 may be dispensedwith. The reference faces 81 may also be dispensed with when thepositioning faces 80 can at the same time serve directly as referencefaces during the manufacture of injection orifices 28.

As already mentioned, the pressure drop in the high pressure zone isdependent on the cross section and accumulator volume of the latter.What is critical for fixing this volume is the cross section which isdetermined by the central housing bore 40 and the nozzle needle 30 andwhich remains constant over a large part of the valve length. Thecross-sectional narrowing within the nozzle body 18 does not cause anyinadmissible long-lasting pressure drop in the high pressure zone duringthe opening of the injection orifices 28, since this cross-sectionalnarrowing extends only about the length of 30 to 40 mm, and, in the caseof an injection time of about 1 ms, the transient time, determining thepressure drop, of the pressure pulsation within this zone of narrowedcross section amounts to only about 30 to 40 μs (according to the soundvelocity in the fuel).

FIG. 5 shows a second exemplary embodiment of a nozzle body 18 a forminga valve seat element and of the arrangement of said nozzle body in thelower housing part 14 a. Once again, a nozzle tip 22 a provided with thenozzle needle seat 26 and with the injection orifices 28 projects out ofthe housing part 14 a. In this exemplary embodiment, there is no unionnut for fastening the nozzle body 18 a in the housing part 14 a, but,instead, the nozzle body 18 a is sealingly pressed from below, in thecorrect rotary position with respect to the housing 14 which is given bythe positioning faces 80, with a press fit 85 into a part 40 a of thehousing bore 40, until said nozzle body comes to bear in the axialdirection against a step face 86 in the housing bore 40. That part 39 ofthe nozzle needle 30 which is provided with the ground-down faces 36 andis guided in the nozzle body bore 32 with a close sliding fit of lessthan 20 μm is shifted nearer toward the lower end 34, as compared withthe exemplary embodiment according to FIGS. 1 and 2, and is located inthe region of the nozzle tip 22 a projecting out of the housing part 14a, that is to say outside the press fit region 85. In the region of thepress fit 85, the nozzle needle 30 is stepped in diameter with respectto the part 39, so that the pressing of the nozzle body 18 a into thehousing 14 does not result in any adverse influence on the nozzle needlemovement.

It would be possible for the ground-down faces 36 connecting the spaces37, 43 to be designed continuously, in a similar way to the versionaccording to FIGS. 1 and 2, but the part 39 would have to be steppedslightly in diameter in the region of the press fit 85, so that theclose sliding fit for nozzle needle guidance is not impaired by thenozzle body 18 a being pressed in.

The nozzle body 18 a or its nozzle tip 22 a is also provided with thepositioning faces 80 described above.

Instead of the positioning faces 80, however, the nozzle body 18 aaccording to FIG. 5 (or its nozzle tip 22 a projecting out of thehousing 14) or the nozzle body 18 according to FIG. 1 to 4 (or itsnozzle tip 22 projecting out of the housing 14) could be provided with acentering countersink (or a plurality of centering countersinks) fordefining its rotary position with respect to the housing 14, asillustrated in FIG. 6 by the example of a nozzle body 18 a′. Thecentering countersink is designated by 82 in FIG. 6. It is a roundcentering countersink 82 which is provided for a centering pin and whichis formed on the circumference of the nozzle tip 22 a′ projecting out ofthe housing part 14 a.

The means for defining the rotary position of the nozzle body 18 or 18 awith respect to the housing 14 could also be formed by a visuallyreadable marking formed on the circumference of the nozzle tip 22 or 22a projecting out of the housing part 14 a. In FIG. 7, a nozzle tip 22′is depicted by a dash marking 83. Instead of a dash (or a plurality ofdashes), however, dots, small circular areas or the like could also beformed as a marking on the nozzle tip 22′.

In the third exemplary embodiment, illustrated in FIG. 8, of a lowervalve part, a nozzle body 18 b, which is relatively short, as seen inthe longitudinal direction, is inserted from below with its uppersleeve-shaped part 21 b into a lower part 90, of stepped outsidediameter, of the housing part 14 a or into a recess 92 of the latter andis supported axially on a supporting face 91. The nozzle body 18 b has anozzle tip 22 b provided with the nozzle needle seat 26 and with theinjection orifices 28. This small nozzle body 18 b, which must behardened, is welded to the part 90, the weld seam being provided betweentwo end faces 96, 97 of these two parts 90, 18 b. The weld seam herealso assumes the sealing-off function. For defining the rotary positionof the nozzle body 18 b with respect to the housing 14 prior to welding,positioning faces 80 are once again formed on the circumference of thenozzle tip 22 b (here, too, a centering countersink 82 or marking 83could be used instead of positioning faces 80). In this exemplaryembodiment, nozzle needle guidance does not take place in the nozzlebody 18 b, as in the variants described above, but in the lower housingpart 14 a. The central housing bore 40 is narrowed in the lower regionto a guide bore 94 in which the nozzle needle 30 is closely guidedslideably with its part 39 having the ground-down faces 36. The guidebore 94 corresponds in its diameter to the nozzle body bore 32 extendingas far as the nozzle needle seat 26. The nozzle body 18 b must be guidedor centered accurately in the recess 92, so that the nozzle needle seat26 is aligned coaxially with the nozzle needle 30 guided in the housingpart 14 a. Moreover, this exact guidance in the recess 92 preventstilting during welding.

The short design of the nozzle body 18 b makes it possible that a shortgrinding arbor can advantageously be used for grinding the nozzle needleseat 26. Moreover, a holding part 16 (FIG. 1, 2) or a press fit 85 (FIG.5, 6) may be dispensed with.

The fourth exemplary embodiment, illustrated in FIG. 9, differs fromthat according to FIG. 8 in that the upper sleeve-shaped part 21 c ofthe nozzle body 18 c has a thin-walled design and projects directly intothe guide bore 94 of the housing part 14 a (that is to say, noadditional recess 92 is provided in the housing 14). By means of thefuel system pressure prevailing within the bore 32 or in the space 37,the thin-walled upper part 21 c is pressed sealingly onto the wall ofthe guide bore 94. The weld seam between the housing part 14 a or 90 onthe nozzle body 18 c needs to absorb only the axial forces here, whilesealing is ensured by the widening part 21 c. Here, too, the nozzle body18 c has positioning faces 80 for positioning in the desired rotaryposition.

In the fifth variant, illustrated in FIG. 10, in comparison with theversion according to FIG. 9, the thin-walled upper part 21 c known fromFIG. 9 is dispensed with in the nozzle body 18 d; the nozzle body 18 dhas been held in a coaxial position to the nozzle needle 30 by means ofa centering sleeve 99 which, on the one hand, projects into the guidebore 94 and, on the other hand, is inserted into the nozzle body bore32, and has then been welded to the housing part 14 a or 90. In thisexemplary embodiment, too, the thin-walled centering sleeve 99 iswidened by the fuel system pressure and is pressed sealingly against thewalls of the bores 32, 94, so that, in this variant too, the weld seamassumes merely the absorption of the axial forces, but not thesealing-off function. The nozzle tip 22 d, too, is equipped with meansfor defining the rotary position with respect to the housing 14 (ifappropriate, with positioning faces 80).

FIG. 11 also shows a nozzle body 18 e welded to the lower housing part14 a or 90, in this version no special structural means being providedfor centering the nozzle body 18 e with respect to the housing part 14a, apart from conically arranged end faces 96, 97 of the housing part 14a, on the one hand, and of the nozzle body 18 e, on the other hand, saidend faces being provided for welding the two parts 14 a, 18 e together.So that, even in this version, an exact coaxial position of the nozzleneedle 30 closely guided slideably in the housing guide bore 94 isensured with respect to the nozzle needle seat 26 of the nozzle body 18e fastened to the housing 14 by means of welding, the welding of thenozzle body 18 e is carried out in the way described with reference toFIG. 12.

The parts 18 e′ and 14 a according to FIG. 12 which are to be weldedtogether differ from those according to FIG. 11 in that the end faces96′, 97′ to be welded together are not conical, but are arranged in aplane perpendicular to the longitudinal axis of the respective part 18e′, 14 a.

To weld the nozzle body 18 e′ to the lower housing part 14 a, the nozzlebody 18 e′ is pressed with a high pressure force F against a countertool102 by means of a positioning tool 101 introduced into the centralhousing bore 40 and the nozzle body bore 32. The positioning tool 101bears with an end portion 104 corresponding to the nozzle needle end 34on the nozzle needle seat 26 and presses the nozzle tip 22 e′ with itsconical part 113 onto a conical counterface 103 of a recess 105 of thecountertool 102. The housing part 14 a is pressed with its end face 96′onto the end face 97′ of the nozzle body 18 e′ with a lower force F1(caused, for example, by spring pretension). The positioning tool 101 isguided exactly within the housing bore 40, but is stepped in diametershortly above the parting plane of the two parts 14 a, 18 e′ to bewelded together (and as far as the end portion 104), so that there issufficient space radially for any welding bead. As indicated by arrows Sin FIG. 12, in the design with the end faces 96′, 97′ lying in oneplane, the countertool 102, together with the nozzle body 18 e′, can bedisplaced laterally, that is to say oriented in the transverse directionwith respect to the positioning tool 101, before the actual weldingoperation commences. In the embodiments according to FIG. 8 to 10, too,welding is advantageously in each case simultaneously carried outsymmetrically at two opposite points.

The advantage of the welding device according to FIG. 12 is that theseat face 26 of the nozzle body 18 e′ is positioned exactly on the axisof the housing part 14 a and, owing to the high pressure force F, isalso held during the welding operation, thus ensuring the functioning ofthe parts after welding.

In the embodiment according to FIG. 12, too, the nozzle body 18 e′ mayhave means for positioning in the desired rotary position.

The countertool 102 or the recess 105 could also be configured in such away that, instead of the acute-angled conical part 113 of the nozzle tip22, the obtuse-angled part 114 of said nozzle tip could also serve forsupporting the nozzle body 18 e or 18 e′.

In the exemplary embodiment according to FIG. 13, too, there is a nozzlebody 18 f welded to the lower housing part 14 a, but this is, here, anextremely small part which forms only the nozzle tip 22 f and which hasthe nozzle needle seat 26 and the injection orifices 28. This nozzlebody 18 f is inserted with its circumferential face 106 from belowdirectly into the central housing bore 40 or into the guide bore 94 forthat part 39 of the nozzle needle 30 having the ground-down faces 36 andis welded from below. The nozzle body 18 f has in its upper region athin-walled lip 107 which is pressed sealingly against the housing innerwall by the high pressure prevailing in the housing bore 40. In thisversion, too, preferably a marking is formed on the circumference of thenozzle tip 22 f projecting out of the housing part 14 a, in order todefine the rotary position of the nozzle body 18 f with respect to thehousing 14.

In all the variants described above, the means according to theinvention for defining the housing/nozzle body rotary position make itpossible to have a slender injector design, specifically both for smalland for large internal combustion engines.

-   -   However, a slender injector design is also possible in the        embodiments of the lower valve part which are evident from FIGS.        14 and 15.

FIG. 14 likewise shows a nozzle body 18 g which is inserted into thecentral housing bore 40 or guide bore 94 and which has, on the one hand,an upper part 108 provided with the nozzle needle seat 26 and with athin-walled sealing-off lip 107 and, on the other hand, a lower part 109provided with a number of axially directed injection orifices 28parallel to one another. The lower part 109 is welded at itscircumference together with the housing part 14 a from below. By meansof the lower end 34, bearing on the nozzle needle seat 26, of the nozzleneedle 30, the space 43 belonging to the high pressure zone and locatedwithin the bore 40 is separated from a space 110 leading to theinjection orifices 28, and the injection orifices 28 are thereby as itwere kept closed. In this version, the defining of the rotary positionof the nozzle body 18 g with respect to the housing 14 is dispensed withcompletely, since the fuel jet injected out of all the injectionorifices 28 into the combustion space of the internal combustion engine,with the nozzle needle 30 lifted off from the nozzle needle seat 26,remains in the same direction in any rotary position, directed axiallywith respect to the fuel injection valve.

The same also applies to the variant illustrated in FIG. 15. Here, anozzle body 18 h provided with a number of axially directed injectionorifices 28 parallel to one another is welded to the lower housing part14 a on the end face. In this version, the nozzle needle seat 26 is notmanufactured in the nozzle body 18 h, but in the housing part 14 a, as alower part of the housing bore 40 or of the guide bore 94. The lowerhousing part 14 a has an end-face recess 111 delimiting the space 110leading to the injection orifices 28. The connection of the space 110 orof the injection orifices 28 to the high pressure zone may again be keptopen or closed by means of the nozzle needle 30 cooperating with thenozzle needle seat 26.

In all the variants, the injection valve member or the nozzle needle 30can be installed in the essentially tubular housing 14 from above in asimple way.

In the embodiments according to FIGS. 14 and 15, it is also conceivableto provide the part 109 or the nozzle body 18 h with a means fordefining the rotary position with respect to the housing duringfastening to the latter. This would have advantages particularly if theinjection orifices 28 or not all the injection orifices 28 were to bedirected axially with respect to the fuel injection valve 1.

It is also possible, instead of the means described further above,formed on the outside, for defining the rotary position of the valveseat element 18; 18 a; 18 a′; 18 b; 18 c; 18 d; 18 e; 18 e′; 18 f withrespect to the housing 14, to use the injection orifices 28 themselvesfor this purpose during the fastening of said valve seat element to thelatter. In this case, the position of one or more of the injectionorifices 28 can be detected by means of a, for example, optical sensor,and the valve seat element can then be brought together with the housing14 in the desired rotary position, for example by means of a robot. Fordetecting the rotary position of the valve seat element, it is possible,for example, to use an image-processing system with, as a sensor, atelevision camera or digital photographic camera, the signals from whichare evaluated by means of a computer and transmitted, processed, to acontrol means for controlling the robot. After the valve seat elementand the housing 14 have been brought together with the correct rotaryposition, the valve seat element is fastened to the housing, asdescribed further above, for example by means of a union nut, by weldingor by means of a press fit. The fastening operation may likewise becarried out by means of a robot.

1-21. (canceled)
 22. A fuel injection valve for intermittent fuelinjection into a combustion space of an internal combustion engine,comprising: a) a housing; b) a valve seat element including a seatprovided with injection orifices; c) means for fastening the valve seatelement to the housing, the valve seat element projecting with a parthaving the seat out of the housing; d) an injection valve memberarranged longitudinally adjustably in the housing and configured tocooperate with the seat; e) a control device for controlling adjustingmovement of the injection valve member; f) a central housing bore thatruns in a direction of a longitudinal axis of the housing and in whichthe injection valve member runs and that is connected to a fuel highpressure connection and to the seat for the injection valve member; andg) that part of the valve seat element that has the seat and projectsout of the housing is provided on its outside with means for defining arotary position of the valve seat element with respect to the housingduring fastening of said valve seat element to the housing.
 23. The fuelinjection valve as claimed in claim 22, wherein the means for definingthe rotary position of the valve seat element with respect to thehousing is formed by a positioning face, centering countersink, orvisually readable marking formed on an outside of the part projectingout of the housing.
 24. The fuel injection valve as claimed in claim 22,wherein the injection valve member is closely guided with a partslideably in a bore, said bore extending as far as the seat providedwith the injection orifices, of the valve seat element, this partslideably in the bore being provided on its circumference withground-down faces, by which the central bore is connected to the seat.25. The fuel injection valve as claimed in claim 22, wherein the meansfor fastening the valve seat element to the housing comprises a unionnut configured to be screwed onto the housing, and a metallic washer isprovided with lapped end faces arranged between an upper face of thevalve seat element and a lower face of the housing.
 26. The fuelinjection valve as claimed in claim 24, wherein the valve seat elementis inserted sealingly by a press fit into a part of the central housingbore and is supported axially on a step face, that part of the injectionvalve member which is provided with ground-down faces being closelyguided slideably in a region of the bore located outside the housing,and, in the press fit region, the injection valve member being steppedin diameter with respect to the part provided with ground-down faces.27. The fuel injection valve as claimed in claim 22, wherein theinjection valve member is closely guided slideably, with a part providedwith ground-down faces, in a guide bore of the housing or of a lowerhousing part, and the valve seat element has a short design, as seen ina longitudinal direction of the fuel injection valve, and is weldedtogether with the lower housing part such that the longitudinal axis ofthe valve seat element is arranged coaxially to an axis of the guidebore.
 28. The fuel injection valve as claimed in claim 27, furthercomprising means for centering the valve seat element with respect tothe housing or to the guide bore.
 29. The fuel injection valve asclaimed in claim 27, wherein the valve seat element is inserted withpart of its outer face from below into the guide bore and is welded intothe guide bore, the guide bore being sealed off by at least one of aweld seam and a thin-walled valve seat element part pressed sealinglyagainst the wall of the guide bore by the fuel system pressureprevailing in the guide bore.
 30. The fuel injection valve as claimed inclaim 28, wherein the valve seat element is welded to the housing on anend face and has a bore that extends as far as the seat provided withthe injection orifices and that is connected to the central housing boreby the guide bore, the means for centering the valve seat element withrespect to the guide bore being formed by a sleeve-shaped thin-walledvalve seat element part projecting into the guide bore from below, thispart projecting into the guide bore configured to be pressed sealinglyagainst a wall of the guide bore by fuel system pressure prevailing inthe bore.
 31. The fuel injection valve as claimed in claim 28, whereinthe valve seat element is welded sealingly on an end face to the housingand has a bore that extends as far as the seat provided with theinjection orifices and that is connected to the central housing bore bythe guide bore, the means for centering the valve seat element withrespect to the guide bore being formed by a sleeve-shaped valve seatelement part projecting from below into a recess coaxial to the guidebore.
 32. The fuel injection valve as claimed in claim 28, wherein thevalve seat element is welded on an end face to the housing and has abore that extends as far as the seat provided with the injectionorifices and that is connected to the central housing bore by the guidebore, the means for centering the valve seat element with respect to theguide bore being formed by a centering sleeve that projects, at a firstend, into the guide bore and, at a second end, into the valve seatelement bore and that is configured to be pressed sealingly againstwalls of the two bores by the fuel system pressure.
 33. A method formounting a valve seat element having a seat provided with injectionorifices in a defined rotary position on a housing of a fuel injectionvalve configured for intermittent fuel injection into a combustion spaceof an internal combustion engine, comprising: detecting a position of atleast one of the injection orifices by a sensor; and positioning thevalve seat element into the defined rotary position as a function of asignal from the sensor and mounting the valve seat element on thehousing.
 34. A fuel injection valve for intermittent fuel injection intoa combustion space of an internal combustion engine, comprising: a) ahousing with a central housing bore running in a longitudinal directionand connected to a fuel high pressure connection; b) an injection valvemember arranged longitudinally adjustably in the housing bore and thatcooperates with a valve seat and by which a connection between thehousing bore and a space leading to injection orifices can be made andbroken; c) a control device for controlling adjusting movement of theinjection valve member; d) wherein the injection valve member is closelyguided with a part slideably in a guide bore forming a lower part of thehousing bore; and e) wherein the injection orifices are manufactured ina nozzle body welded to the housing.
 35. The fuel injection valve asclaimed in claim 34, wherein the nozzle body is inserted into the guidebore from below and is welded on its circumference together with theguide bore, a part which forms the valve seat being arranged in theguide bore above the nozzle body and being pressed against the nozzlebody by the fuel system pressure prevailing in the guide bore, and witha thin-walled sealing-off lip against a wall of the guide bore.
 36. Thefuel injection valve as claimed in claim 34, wherein the nozzle body iswelded together with the housing on an end face, and the valve seat isformed by a conically narrowing part of the central housing bore, saidpart being adjacent to the guide bore.
 37. A fuel injection valve forintermittent fuel injection into a combustion space of an internalcombustion engine, comprising: a) a housing; b) a valve seat elementincluding a seat; c) the valve seat element connected to the housing bya union nut configured to be screwed onto the housing, such that saidvalve seat element projects with a part having the seat out of thehousing; d) an injection valve member arranged longitudinally adjustablyin the housing and cooperating with the seat; e) a control device forcontrolling adjusting movement of the injection valve member; f) acentral housing bore that runs in a direction of a longitudinal axis ofthe housing and in which the injection valve member runs and which isconnected to a fuel high pressure connection and to the seat; g) theinjection valve member is closely guided with a part slideably in a boreof the valve seat element, said bore extending as far as the seat; andh) a metallic washer arranged between an end face of the valve seatelement and a lower face of the housing.
 38. The fuel injection valve asclaimed in claim 37, wherein a thickness of the washer is selected suchthat the injection valve member executes a predetermined maximum strokeduring opening and closing of the valve.
 39. A fuel injection valve forintermittent fuel injection into a combustion space of an internalcombustion engine, comprising: a) a housing with a central housing borerunning in a longitudinal direction and connected to a fuel highpressure connection; b) a valve seat element including a seat; c) aninjection valve member arranged longitudinally adjustably in the housingbore and cooperating with the seat; d) a control device for controllingadjusting movement of the injection valve member; e) the valve seatelement is inserted sealingly with a press fit into a part of thecentral housing bore and is supported axially on a step face, a part ofthe valve seat element that has the seat projecting out of the housing;f) the injection valve member is closely guided with a part slideably ina bore of the valve seat element, said bore extending as far as theseat; g) that part of the injection valve member which is closely guidedslideably in the bore of the valve seat element has on its circumferenceground-down faces, by which the central housing bore is connected to theseat; h) that part of the injection valve member that is closely guidedslideably in the bore of the valve seat element is located in a regionof the valve seat element that projects out of the housing; and i) theinjection valve member is stepped in diameter in the press fit region ofthe valve seat element.
 40. A method for fastening a valve seat elementwith a central bore and a valve seat to a housing, provided with acentral housing bore, of a fuel injection valve, the valve seat beingprovided for cooperation with an injection valve member arrangedlongitudinally adjustably in the housing bore, the method comprising:placing the valve seat element onto a countertool corresponding in itsshape to it and pressing with a pressure force onto the countertool by apositioning tool that corresponds in its form essentially to itsinjection valve member and that is guided in a guide bore of thehousing, said guide bore being provided for the injection valve memberand forming part of the central housing bore; pressing end faces of thevalve seat element and of the housing against one another with a lowerforce; a welding operation, simultaneously at two opposite points, in aregion of end faces on a circumference of the parts to be connectedtogether.
 41. The method as claimed in claim 40, wherein a radial gapfor a welding bead is provided in the region of the end faces betweenthe positioning tool and the parts to be connected.
 42. The method asclaimed in claim 40, wherein, with the end faces lying in one plane, thepositioning tool is stepped in diameter in the region of the end facesand in the region lying below them and extending as far as the valveseat, and the countertool, together with the valve seat element, can beadjusted in a transverse direction prior to the welding together and canthus be aligned radially with respect to the positioning tool.